Micrometer



J. BROATCH Dec. 24, 1957 MICROMETER Filed Nov. 22, 1954 M H n w M N m M N A H O J MICROIWETER John Broatch, Vancouver, British Columbia, Canada Application November 22, 1954, Serial No. 470,434

2 Claims. (Cl. 33143) My invention relates to improvements in micrometers.

The objects of the invention are to provide a micrometer which is compact so that it can be used in any situation where exact measurements are to be taken; to provide a device which can be applied to an object to be measured, adjusted to the desired dimension instantly and if necessary, removed from the work to a position where its scale can be conveniently and accurately read, and also to provide a micrometer which can be opened up to its full range without efiort and in a moment of time.

Still further objects are to provide such a device which cannot be closed with suflicient force upon its work as to give an inaccurate reading, and to provide a device which is no more cumbersome in shape or size than the conventional micrometer with a graduated screw threaded plunger.

Referring to the accompanying drawings:

Figure 1 is an elevational view of the invention.

Figure 2 is a fragmentary view showing the plunger barrel in section.

Figure 3 is a part rear elevational view showing the graduated sleeve stop.

Figure 4 is a transverse sectional view taken on the line 4-4 of Figure 3.

In the drawings like characters of reference indicate corresponding parts in each figure.

The numeral 1 indicates the micrometer body consisting of a yoke 2 of conventional shape supporting an anvil carrier 3 and a plunger barrel 4. The anvil carrier is of conventional form and carries an anvil 6 which may be adjusted, if necessary, to take up wear and to correct any inaccuracy resulting therefrom.

The barrel 4 is fitted with an apertured base 8 and an apertured screw cap 9 at its upper end. A window opening 10 is provided in one side of the barrel 4, see Figure 1, which may be provided with a glass panel 12 for the purpose of excluding dust or cuttings from the interior of the barrel. Slidably mounted in the barrel 4 and passing through the apertures of the base 8 and the cap 9 is a plunger 14 to which a flange 15 is secured by brazing or otherwise. This flange is adapted when the plunger 14 is fully retracted to contact a stop ring 17 formed on the inner side of the screw cap 9. A coil spring 18 abuts the base 8 and thrusts against the flange 15 to return the plunger 14 to retracted position as shown.

Slidably but non-rotatably mounted in the barrel 4 is a sleeve 20 having an inturned flange 21 at its upper end. The flange 21 is engaged on its underside by a coil spring 22 which is carried on the base 8 to carry the sleeve 20 to its normal or retracted position, with its inturned flange 21 in contact with the flange 15 of the plunger 14.

Mounted on the rear face of the yoke 2 is a spring leaf 25 which is provided with a curved lip 26, see Figure 4, to form a brake 27. The barrel is provided with a rectangular opening 29 to enable the lip to bear upon the periphery of the sleeve 20 and normally hold it against endwise movement in the barrel. The brake 27 is enclosed in a cover 30, see particularly Figure 4, which may be attached to the yoke as indicated in dotted line in Figure 3. A push button 31 is slidably carried in the yoke and is adapted to be pressed to release the tension of the brake 27 and to allow the spring 22 to act upon the sleeve 20 to return it to retracted position when desired. A set screw 32 extends through the cover 30 to engage the brake spring leaf 25 to adjust the tension on the brake, if desired.

If it is desired at any time to hold the plunger against the retracting action of the spring 18, a thumb screw 33 is fitted transversely into the base 8 to bear upon the side of said plunger.

One side edge of the window opening 10 is provided with a graduated scale 35 which is preferably in fortieths of an inch and the sleeve 20 is provided with a vernier scale of appropriate divisions to enable the plunger movement to be gauged in thousandths of an inch. Since the vernier scale reading is common on measuring devices and is therefore well known, no description of its use is deemed necessary in this specification.

In use, assuming the horizontal wall 60 of a recessed member 61, such as is indicated in dotted lines in Figure 1, is to be measured, the member 61 is placed onto anvil 6 and the plunger 14 is pressed down to engage the surface of the horizontal wall 60, thus moving the sleeve 20 down against the action of the brake 27 to the required distance; if the top of the plunger is released the spring 18 will return the plunger to its normal position and leave the sleeve unmoved, so that the tool can be removed, if desired, to read the scale and determine the thickness of the wall 60. When the dimension is read, a pressure on the push button 31 will release the brake from the sleeve and permit the spring 22 to return it to normal position with its zero in line with the 1" reading on the scale 35 indicating that the distance between the anvil and the adjacent end of the plunger is one inch.

What I claim as my invention is:

1. A micrometer comprising a yoke supporting an anvil and a barrel aligned therewith, a plunger slidable within the barrel adapted to be moved by direct manual thrust towards the anvil and a spring to return the plunger to normal position, said barrel having an opening, a gradulated scale upon the barrel adjacent the opening, a member within the barrel having a complementary scale exposed within the opening, said member being adapted to be read with the graduated scale, said member being movable in one direction in response to plunger movement, a second spring for returning the member to normal position and a manually releasable brake normally engaging the member to retain it in the position to which it is moved by the plunger against the thrust of the second spring.

2. A micrometer comprising a yoke supporting an anvil and a barrel aligned therewith, a plunger slidable within the barrel, adapted to be moved towards the anvil by manual thrust, a spring to return the plunger to normal position, said barrel having an opening, a graduated scale upon the barrel adjacent the opening, a sleeve concentrically mounted about the plunger for sliding movement within the barrel, means on the plunger normally engaging the sleeve to impart endwise movement to the sleeve as said plunger is moved towards the anvil, a second spring for returning the sleeve to normal position, a normally engaged brake for holding the sleeve stationary against the thrust of its spring mean during the return of the plunger to normal position, and means for manually re leasing the brake from the sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 423,284 Smith Mar. 11, 1890 FOREIGN PATENTS 103,015 Germany May 12, 1899 

